Field of the Invention
The invention relates to a communication method for interworking between a cellar communication network and closed subscriber group (CSG) cells and, particularly, the invention relates to a communication method, an access network device and a communication device using the same method, and a communication system.
Description of Related Art
Closed subscriber group (CSG) cells (femto cells, also called Home eNodeB) are supported in wireless communication standards such as Third Generation Project Partnership (3GPP) Long Term Evolution (abbreviated as LTE hereinafter). The LTE CSG cells can be deployed with a code division multiple access (CDMA) macro cell coverage. The LTE CSG cells can be energy efficient since its radio service coverage is much smaller than the CDMA macro cell coverage. However, in current CDMA standards such as evolved high rate packet data (eHRPD) specification, the interworking between a CDMA macro cell evolved access network device (eAN) and LTD CSG cells is not supported.
As previously mentioned, the LTE CSG cell coverage area is much smaller than a macro cell coverage area, there might be a lot of LTE CSG cells deployed and being in operation within an eHRPD macro cell coverage. If LTE CSG cells are treated as normal eHRPD macro cell eAN devices, power consumption will be a major issue since an evolved access terminal (eAT) may keep searching for CSG cells within an eHRPD macro cell coverage. Therefore, it is a major concern to develop a communication method for providing an interworking between the eHRPD macro cell eAN and LTE CSG cells.